.pic-item {
  position: relative;
  display: inline-block;
  width: 100px;
  overflow: hidden;
  font-size: 0;
  border-radius: 10px;
  background-size: cover;
  background-repeat: no-repeat;
}

.pic-item::before {
  content: ' ';
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  cursor: pointer;
  background-color: rgba(0,0,0,0.5);
  transition: all .3s;
  z-index: 1;
}
.pic-item:hover::before {
  opacity: 1;
}
.pic {
  width: 100%;
  width: 100%;
}

.preview-box {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  opacity: 0;
  background-color: #000;
  transition: opacity .36s ease-in-out;
  z-index: 1000;
}
.img {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  margin: auto;
  max-width: 100%;
  max-height: 100%;
  border-radius: 10px;
  z-index: 1002;
}
.img.active {
  transition: all .36s ease-in-out;
}